We document the coexistence of ferro- and anti-ferromagnetism in pyrochlore $rm Yb_2Ti_2O_7$ using three neutron scattering techniques on stoichiometric crystals: elastic neutron scattering shows a canted ferromagnetic ground state, neutron scattering shows spin wave excitations from both a ferro-and an antiferro-magnetic state, and field and temperature dependent small angle neutron scattering reveals the corresponding anisotropic magnetic domain structure. High-field $langle 111 rangle$ spin wave fits show that $rm Yb_2Ti_2O_7$ is extremely close to an antiferromagnetic phase boundary. Classical Monte Carlo simulations based on the interactions inferrred from high field spin wave measurements confirm $psi_2$ antiferromagnetism is metastable within the FM ground state.
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